Studies on the hemeproteins, hemoglobins, myoglobin, catalase, peroxidase and cytochrome P-450 will be carried out in order to determine the mechanism of action of oxygen storage, transport and activation and the mechanisms of electron transport. These enzymes and simple metal- loporphyrins will be studied using electrochemical, kinetic, optical and magnetic resonance techniques. The goals are an understanding of the structural and electronic effects which govern the proper functioning of these proteins. Various dimeric porphyrins have been prepared to answer these questions and another series of dimeric porphyrins will be prepared to answer these questions and another series of dimeric porphyrins will be prepared for use in photodynamic therapy treatment of cancer. Water soluble hemes, capable or reversibly binding dioxygen will be studied as possible blood substitutes.